Potential solutions to further increase the information throughput in optical communications systems, and thus sustain the ever-increasing demand for data transmission, have been proposed, and they include: the use of an alternative optical fibre designs with an air core, free of fibre nonlinearities [1]}; the use of new degrees of freedom to transmit information, namely space (space division multiplexing or SDM) [2]}; and, finally the expansion of the transmission bandwidth in current SMF-based systems [3]}. The latter approach is one capable of readily reusing existing fibre infrastructure and may well be the most viable option, considering the latest advances in optical subsystems [4]}.
